Areas to the west and southeast of Rochester are now listed in severe drought — an unusually harsh classification rarely seen in temperate upstate New York.

As the summer of 2016's drought worsens, the western portions of Orleans, Genesee and Wyoming counties have been downgraded to severe in the U.S. Drought Monitor report released Thursday morning. So have Yates, Tompkins, Schuyler, southern Seneca, northern Chemung and parts of several other counties.

Half the Finger Lakes region is now in the severe-drought category.

There is no end to the hot, dry weather in sight. The forecast for the coming week is for warm temperatures and no chance of rain save for possible thunderstorms Monday.

Beyond that looms a significant heat wave — the arrival of a "massive heat dome" that could bring record high temperatures to the central United States. The effects will be felt in upstate New York as well.

"Part of that clips western New York. Even if we’re at the fringe of it, there’s a high likelihood we’ll be above-normal, too," said National Weather Service meteorologist Aaron Reynolds in Buffalo.

Severe drought, the third-driest of five classifications in the Drought Monitor system, is a relative rarity here. Since 2000, when the weekly monitor reports began, New York state has experienced severe drought only four other times, most recently in the spring of 2012. The last time such a large portion of the state was categorized as in severe drought was in the fall of 2007.

U.S. Drought Monitor report of July 14, 2016.(Photo: U.S. Drought Monitor)

The rest of the region remains in "moderate drought" except for northeastern Monroe and all of Wayne County, which are listed as "abnormally dry."

Rochester measured only 7.22 inches of rain from March through June, or 63 percent of normal. That's the 12th driest March-June period since record-keeping started here in 1871.

Other locations are worse off. Batavia, Ithaca and Elmira, which are in the severe-drought area, are among the monitoring stations that have experienced the driest March-June period on record, said Jessica Spaccio, a climatologist with the Northeast Regional Climate Center in Ithaca.

"It’s been quite a while since we’ve seen things this extreme," she said.

Passing thunderstorms have provided a bit more moisture to some areas, including Rochester and Ithaca.

"We need consequential rains, not just quick-hitting thunderstorms," said Reynolds, the weather service meteorologist. "We need something that gives the entire area significant precipitation, and we’re just not getting that."